Lecture 1,2 & 3 Readings
Sunday, January 13, 2013
Has complexity increased during organismal evolution?
Are mammals more complex than reptiles?
- Genome Size or total number of genes in an organism
- Gene (copy) Number or number of copies of a gene in a given gene family
resulting from gene duplication.
- Increase in the size of organisms over the course of evolution
- Number of genes that encode proteins
- Number of parts or units in an organism (parts might be segments, organs,
- Number of cell types possessed by an organism
- Increased compartmentalization specialization, or subdivision of function
over the course of evolution
- Number of gene, gene networks or cell-to-cell interactions required to
form the parts of an organism
- Number of interactions between the parts of an organism, reflecting
increasing functional complexity and/or integration over the course of
Increase in Number of Types of Cells:
- Mostly seen in animal embryonic development, transformation from a single-
celled zygote to a multicellular organism.
- Most commonly used metric of complexity is the number of different types of
cells possessed by an organism.
- Number of cell types has increased through evolution
Increase in Organismal Size:
- Embryonic development is accompanied by increasing size
- No sustained size increase occurs within many lineages (why this isn’t used
- Evolution often leads to decrease in size
- Different organisms of the same size can show different levels of complexity
- Parasite life cycle may become very complex and involve many intermediate
hosts. There is an adaptive advantage to this life style, the parasite can build
up population numbers in intermediate hosts, enhancing the parasite’s
chance of infecting primary host. It also conserves resources of primary host
so the adult parasite can remain productive for long periods. The Physical Nature of Light
Light serves two important functions in life:
1. Source of energy that can sustain virtually all organisms.
2. Provides organisms with information about the physical world that
- Single cells photosynthetic eukaryote.
- Each cell contains single large chloroplast that harvests light energy and uses
it to make energy-rich molecules through photosynthesis.
- Each cell contains a light sensor called an eyespot that allows individual cells
to gather information about the location and intensity of a light source.
What is Light?
- Portion of the electromagnetic spectrum humans can detect with their eyes.
- Visible light is very narrow portion of